By weighing animals daily or twice daily, body weight trends can be obtained. From these trends it can be deduced whether an animal or a group of animals loses or gains body weight over a number of days. However, body weight trends have less importance for herd management as the body weight can change due to changes in body fat, frame size, gut size, udder size, pregnancy status, and intake of food and water.
Body condition scoring is a method of evaluating fatness or thinness in cows according to a scale, e.g. a five-point scale, where a score of one denotes a very thin cow, while five denotes an excessively fat cow. Research and field experiments have shown that body condition influences productivity, re-production, health and longevity. Thus, thinness or fatness can indicate underlying nutritional deficiencies, health problems, or improper herd management. As a mean to detect problems within the herd, body condition scoring is a good aid in improving the health and productivity of a dairy herd, when done on a regular basis, thus acting as an efficient tool in good herd management.
Determining gut fill levels of the rumens of animals can also assist in the herd management. US 2010/0154722 A1 relates to a system for managing a group of animals, and discloses a 2D/3D camera arranged straight behind or obliquely to the left behind a cow to observe a part of the cow. In one embodiment, the 2D/3D camera forms a depth-image of the left side, on the basis of which a central processing unit determines a score which is representative of a content of the paunch. On the basis of the score for the paunch contents of the cow in question, the central processing unit subsequently generates control information which is related to the feed intake of the cow in question on the relevant day. At a low score, which means that the cow has eaten little to nothing, the control information comprises a signal for a user that the cow in question should be separated because of possible illness, is not allowed to have access to feed, and/or is on heat.